digestive system: accessory organs

salivary glands

exocrine glands that secrete saliva into oral cavity

saliva produced for

speech, taste, chewing, swallowing, digestion

parotid glands

serous, watery --> rich in enzymes

submandibular glands

seromucous --> mix of enzymes + mucous

sublingual glands

mostly mucous -- provide lubrication

serous cells

watery saliva w/enzymes

mucous cells

secrete viscous saliva rich in mucins for lubrication

myoepithelial cells

surround acini + ducts, contract like smooth muscle to push saliva

demilunes

crescent-shaped clusters of serous cells

what do demilunes do

cap mucous acini in mixed glands

pancreas

both exocrine + endocrine functions

exocrine pancreas

acinar cells secrete digestive enzymes, delivered to duodenum in duct

endocrine pancreas

pancreatic islets, secrete insulin + glucagon in blood

acinar cells secrete

digestive enzymes in zymogen granules + HCO3- to neutralize stomach acid

zymogen granules contain

trypsinogen, amylase, lipase, nuclease

liver

- synthesizes plasma proteins

- stores + converts vitamins

- detoxifies

- produces bile for fat digestion + absorption

- regulates hormones

- support metabolic pathways

liver structure

hexagonal lobules w/ branch of hepatic artery (oxygenated blood), branch of hepatic portal vein (nutrient-rich blood from intestines), bile duct

liver blood flow

portal triads --> sinusoids --> central vein

sinusoids function

carry mixed blood to central vein

bile canaliculi

carry bile in opposite direction

kupffer cells

line sinusoids + filter blood

perisinusoidal space

separates hepatocytes from sinusoid endothelium

ito cells

reside in perisinusoidal space + store vitamin A and fat

hepatocytes rich in

RER, SER, mitochondria, glycogen

hepatic sinusoid blood flow

slow + open --> optimized for exchange + immune surveillance

biliary tract

hepatocytes secrete bile --> bile canaliculi --> bile ductules --> intrahepatic bile ducts --> left + right hepatic ducts --> common hepatic duct --> cystic duct --> gallbladder

but also common hepatic duct --> pancreatic duct --> duodenum at major duodenal papilla

gallbladder

stores bile

- contraction triggered by CCK

- simple columnar epithelium